Guys,
I will be installing my new 400 soon. I was wondering if EFI is worth adding and what the benefits are. Throttle response, gas mileage? What $ can I expect to spend and is it worth the money. Also, what systems are recommended.

 

I've installed several of the Holley HP systems. I can't say enough good about the system and how it works. The programming is excellent. You can do anything you want with it or let it tune itself.

Throttle response and driveabilty will be great and fuel mileage will be better. Ultimate HP won't change much just because it's EFI...but you can often get by with a larger intake to feed the cubes and make power that will still drive great at low speeds. Same idea with heads and cam. The EFI allows you to use *racier* parts and still keep driveability great. Or just be even crisper with milder parts.





JIM

 

I have it on my 427 SB.

With the Dart Pro1 CNC heads, which have huge ports and large valves, i can motor around the neighborhood at 20 MPH in top gear at 1200-1400 RPM if I want.

There is NFW that i could do that with a carb, with the intake port size,and cam I have.

Only comments i have are, pro tuner with a chassis dyno can tune it better than the computer can in many cases to extract maximum HP and drivability throughout the RPM range,and,

Don't recirc the fuel through the engine compartment on a C1, it will get the gas too hot in the tank.

You may need to add some Marren pulse dampers on the fuel rails when you dead head the fuel to the rails, when the the regulator is back by the tank to avoid some harmonic fuel pulse reversion issues.

Did I mention my motor makes 400 ft-lb of torque at 1400 RPM, and you can stomp the throttle from that RPM in top gear and it won't bog, sputter or do any other obnoxious thing?

Doug

 

I know it is hard to guess but can you give me an idea of the cost. My mechanic has said around 5K.

 

I'm thinking of putting a Projection111 unit on one of my vehicles. The unit costs about $1800.00. I'm thinking this unit because it has a model where a return line is not needed, making for easier installation. There was an article in Enthusiast mag. where they installed one on a C1.
Tom

 

Woods,

There are many cost options to go down. I'm guessing your working with John at CC. At $5k he is probably giving you the Acell DFI set up which is really nice. If it's what I'm thinking, then its a fair price

You have a lower cost option which is putting it together with different pieces, using OEM parts. For example, you can put on a late 80's C4/Camaro TPI unit which has a OBD1 style ECU (this is the cheapest approach). You can buy the ECU off a used car for dirt cheap. You can get the intake, plenum, fuel rails, etc used also. You need a new distributor that's computer controled along with all kinds of sensors, that can also be bought used. So what I'm saying is there's a low budget way in (probably around $1500k in parts) that will work real nicely, or you go with the aftermarket options that are closer to $3-4k in cost. With either option your then looking at installation cost, unless your doing it yourself.

If you go the OBD1 method, the downside is programing. It's not user friendly programing and there are few people that do it. John's got someone that does it, and he did mine. Real good work. With the OBDII and the aftermarket alternatives, you get much easier programing.....and as mentioned above automatic tuning. These options will allow you, along with a laptop, to do your own tuning and analysis.

John did all the work on my car. We started with the TPI/OBD1 approach because back in the day, it was the only option (20 years ago).



Four years ago, I upgraded the TPI hardware with the TPIS TPI Miniram. This upgrade cost about $1200 for parts, and then it worked with my ECU. This was a real nice improvement in HP and Torque.



I often consider upgrading my ECU to the DFI or other aftermarket options, but I just can't justify the cost vs benefit. Good luck with your decision

EFI all the way!

 

i have the Accel Thruster DFI system and there were many times when, while trying to tune, i wanted to find a tall building to jump off from.... automatic tuning would be nice...

Bill

 

If you go to a fuel injection system here is a forum that is very helpful:
http://www.chevytalk.org/fusionbb/sh...uel_Injection/
One of the members of this forum works for Holley and did a lot of development work on their new systems.

Charles

 

Forum member 67-427ci loves EFI and has tested a few. He is currently installing the MSD Atomic system in his Corvette. I'm sure a report is forthcoming.

 

I have a Projection III that just arrived this week. I have everything (kit, hose, AN fittings, etc) $1800. I am installing it on my 74 Avanti which has a 400 SBC. The Avanti has a return fuel line. I welded the O2 bung into the exhaust this afternoon. Hope to have installed and running within a few days.

I will report you how it goes.

Joe

I know, it is not a Corvette but it is sort of like a C-1 with a back seat.

 

I had read about this system several months ago and when MSD started shipping the I decided to go for it. http://www.atomicefi.com/home.aspx

This is a new system that can be installed by itself or with one of MSD's distributors so it controls timing as well. FYI their 8572 tach drive distributor fits under the shielding and drives the tachometer properly. Right now they are offering a free MSD Digital 6A box with the purchase of the unit.

One of the best features is it fits under our stock Corvette air cleaners and the factory linkage connects perfectly without modification. I mounted the Digital 6A box under the passenger side fender above the battery and the EFI power module is on the firewall. There is plenty of cable and wires to mount this module under the fender too.

I finished the Atomic installation on my 67 Coupe a few days ago. At first I was going just install the Atomic unit and setup the timing later, then I decided to do it all right away. First off MSD has done a terrific job putting this kit together, nothing has been left out of it.

Since I drive my Corvette all around the USA I mounted the pump in the tank to avoid any possibility of heat related issues and setup the returnless fuel system. While I was running the new fuel line I also plumbed in the original steel line to be a return line in case I have a need to change it. To make it a return system all I need to do is add one line and a regulator in the front.

I installed MSD's 8572 tach drive distributor with the Atomic system and the plugs are gaped at .050" for the Digital 6A box.

Once everything was connected and I had fuel in the tank I cycled the key a few times to build pressure and made sure there were no leaks. On the first start I was impressed that it started immediately without hesitation. First off I locked the timing and set it to 15* on the timing mark. Initially it was advanced a bit much at 25* so I brought it back to 15* and locked the distributor. After it was set I ran it at different RPM's and checked the timing against the hand held display and it is right on target. After that I got the idle settled down so the IAC is open less than 20 points.

Once that was done it was time to drive it and I am again impressed. It is much more responsive than a carburator and after driving it about 20 miles it settled in nicely.

This is my third experience with aftermarket EFI, my first was with PowerJection III which I installed on my 66 Impala Big Block Pro Touring car, it was a pain in the a$$ and after two months of trying to get it running properly I returned it. Then I installed a MassFlo EFI system on the Impala which is flawless in the way it runs. Now the Atomic System is equally as good as my MassFlo system. We are driving the Corvette to Tahoe, CA in September and I am already looking forward to how it will run in the mountains.

Update: I now have about 150 miles on it and it is amazing how well it runs. Hot or cold just twist the key and you are ready to go as it runs the same (just like a new car).

Here are a few videos of how it starts and idles.

http://www.youtube.com/watch?v=m4Pt36hfI1k

http://www.youtube.com/watch?v=Yf74QYIxPm4

 

MassFlo is a great system as 67-427 mentioned above. His MasFlo is on an Impala. But they use a high rise single plane intake as part of their system and needs some special work to fit under a mid year small block hood. And no stock air cleaner! See my avatar.
You mentioned value of EFI. You would have to drive a lot of miles to recover the cost (fuel economy) of one of these systems. But the benefits if you drive a lot make for a much nicer dependable driver like a new car. No way to put a value on that.

 

I agree, the value of EFI is in how you use and drive your car or if you just want it to run like a new car. On my Impala (with Mass-Flo) I had to shave the top of the intake manifold .300" and modify the base of a flat base air cleaner to get enough clearance. Mass-Flo EFI will never fit under a mid year hood with a big block. The linkage is different too. That's why I chose the Atomic system for my 67. Our stock air cleaners fit perfectly and hood clearance is the same as a stock carb.
Roy

 

the pictures seem to show what i would call an 'electric carburetor', not an EFI system; i call an EFI system one that has injectors in each intake port.

see AZDoug's post #8 in this thread, see the fuel rail and injectors

http://forums.corvetteforum.com/c1-a...er-engine.html

Bill

 

To me they're both EFI. One is Throttle Body FI and one is Multiport FI.

 

Throttle body EFI has been used on cars since the 80's (or possibly earlier). A carb dumps fuel in the manifold based on how it is jetted. This system (like all EFI systems) reads the exhaust O2 level, manifold absolute pressure, engine coolant temperature, intake air temperature, etc. to determine how much fuel to inject. I have a multiport Mass-Flo EFI system on my 66 Impala and both of these system run equally well. Plus both of these systems control the timing as well. Far from a electric carb.
Roy

 

Roy, both you and PP are correct in all that you say, and i stand corrected; but throttle body EFI still has the same problems in fuel distribution that a carb/manifold combo has and not the precision of individual injectors.

EFI has been evolving: throttle body, then multi-port, and the latest is direct injection into the cylinder. each iteration seems to be focused on more precisely metering fuel usage.

Bill

 

Sequential timed port fuel injection can be tuned to make a motor that would otherwise be undrivable on the street at any reasonable RPM, behave very well. A fuel injected carburetor replacement, while being able to keep your AFR fairly consistent, will not provide the tune-ability benefits.

If your motor runs great with a carb, the electric carb/EFI gizmo will work fine for you.

When i went from direct port injection batch fire, to sequential timed port injection, using the same manifold, rails and injectors, the car idled and ran more smoothly in the under 1500 RPM range. I doubt my motor would idle at all under 1500 RPM, if I didn't use port EFI, or if it did, it would have to be too rich, and it would have a bad off idle part throttle stumble.

Doug

 

This is all very interesting. It sounds like the way to go is multi port injection. What I would want to accomplish is dirveability and better fuel mileage.
From what I have read it will involve an addition of a return fuel line, an in tank pump, control module, C02 sensor. It sounds like a lot of the cost is in labor. I will most likely have it done by Corvette Conspiracy.
I will be installing the new carbuerated 400 soon. I will most likely run it this summer and work on the EFI next winter.
Thanks for the input

 

lol... no guarantees on better mpg, the fuel system may be high tech but the engine itself isn't... whatever mileage gain you see won't hold a candle to what an LS engine gets with EFI.

i had grand expectations of BIG mpg numbers but they aren't much better, or even as good as, that what i got with the rochester FI.

what i did get was EXCELLENT driveability...
Bill